Small (<20 mm) enhancing hepatic nodules seen on arterial phase MR imaging of the cirrhotic liver: clinical implications

OBJECTIVE: To determine the significance in patients with cirrhosis of small (<20 mm) hepatic nodules that show no hyperintensity on T2-weighted MR images but that enhance during arterial phase MR imaging, we reviewed the cases of patients with such nodules. MATERIALS AND METHODS: Our review of radiology reports yielded 68 nodules in 40 patients with cirrhosis that showed no hyperintensity on T2-weighted MR images but had rapid enhancement during arterial phase MR imaging after administration of a gadolinium contrast agent. Thirty-four patients (60 nodules) had multiple follow-up MR imaging examinations (range of length of follow-up, 1-72 months; average length of follow-up, 15 months 2 weeks). The final diagnosis of the nodule was determined by pathology reports or after at least 2 years of follow-up to ensure nodule stability and, therefore, benignity. Two radiologists independently reviewed MR images of the nodules, noting the size, signal intensity on T1- or T2-weighted images, and homogeneity of contrast enhancement. RESULTS: Nine (13%) of the 68 nodules were hepatocellular carcinomas (HCCs). The size of nodules on the first MR examination was between 4 and 20 mm (mean size, 9.5 mm). No significant correlation between the diagnosis of HCC and nodule signal intensity (p = 0.48) or contrast enhancement homogeneity (p = 0.56) on first MR examination was found. Positive predictive value (PPV) and negative predictive value (NPV) for diagnosing HCC on the basis of nodule growth were 100% and 98%, respectively. For diagnosing HCC on the basis of a change in nodule signal intensity, the PPV was 60% and the NPV was 91%. For diagnosing HCC on the basis of a change of enhancement homogeneity, the PPV was 63%, and the NPV was 94%. CONCLUSION: A finding of growth in small, early-enhancing nodules in patients with cirrhosis is highly predictive of HCC. When small nodules are observed on a single examination, close follow-up of the patient appears appropriate.     

平扫和动态增强MR诊断肝脏增生性结节

目的 总结增生性结节(DN)在MRI平扫及动态增强扫描中的特征. 资料与方法 回顾性分析行Gd-DTPA动态增强MR检查并经手术病理证实的DN共11例16个病灶,观察病灶的大小、信号强度、强化方式和时间,测量各序列病灶及周围肝组织的信号强度和背景噪声标准差,计算信噪比及其差值.绘制病灶和周围肝组织的时间-信号强度曲线. 结果 16个病灶中有4个表现为"结中结",中央结节为T1WI低、T2WI等或高信号,动态增强为速升速降或速升缓降型,周围为T1WI高、T2WI等或高信号,动态增强为缓慢上升型;余12个病灶在T1WI上高、等和低信号均有,在T2WI上为等信号和稍高信号,动态增强过程中动脉期强化较明显,门静脉期以等信号为主,延迟期为等及稍高信号, 未见呈低信号者.时间-信号强度曲线显示病灶为速升缓降型. 结论 "结中结"征象和动态增强早期强化、后期与周围肝组织类似信号的表现是DN的MRI特征.     

肝硬化结节与小肝癌的CT、MRI诊断

在肝硬化结节及小肝癌的早期诊断方面,CT、MRI仍是目前临床工作中最重要的方法,本文阐述肝硬化结节演变为肝癌过程中的几个重要环节的CT、MRI表现及国内、外对此的研究现状,这几个环节包括肝硬化再生结节、发育不良性结节(低、中、高级)、小肝癌及肝癌,它们在CT、MRI表现上各有特征,但相互间也有影像学表现上的重叠,故多数较典型者可以通过CT密度值、MRI信号值及增强表现判断其性质,少部分诊断有困难的病灶可以通过双动脉期扫描、MR菲立磁增强及灌注成像等方法提供更多的诊断信息。     

Effect of superparamagnetic iron oxide-enhanced MRI of the liver with hepatocellular carcinoma and hyperplastic nodule

PURPOSE: To evaluate the possibility of superparamagnetic iron oxide (SPIO)-enhanced magnetic resonance imaging (MRI) of the liver in predicting the histologic grade of hepatocellular carcinoma (HCC) and differentiating HCC from benign hyperplastic nodule (HPN). MATERIALS AND METHODS: Thirty patients with 31 histologically proved HCC and HPN underwent MRI (1.5 Tesla). HCCs were graded into well-differentiated HCC (HCCw; n = 10) and moderately to poorly differentiated HCC (HCCmp; n = 15). HPN was categorized into dysplastic nodule (DN; n = 1) and focal nodular hyperplasia (FNH; n = 6). T2-weighted fast spin echo images were obtained before and after administration of SPIO. Signal-to-noise ratios (SNR) of the lesion and surrounding liver parenchyma and contrast-to-noise ratios (CNR) were calculated pre- and postcontrast study. Relative enhancement ratios (RER), also known as signal intensity reduction ratios of the lesions, were also calculated. RESULTS: HCCw, HCCmp, DN, and FNH decreased in SNR after injection of SPIO. RER of HCCw was 19.5 +/- 13.3%, that of HCCmp was 6.8 +/- 5.8%, DN was 44.0%, and FNH was 42.9 +/- 4.8%. Significant statistical differences were seen between HCCw and HCCmp and HCC and HPN in RER. HCCw, HCCmp, and DN increased in CNR, and FNH decreased in CNR, but no lesion showed a statistically significant difference in CNR. CONCLUSION: SPIO-enhanced MR images may help to predict the histologic grade of HCC and distinguish HCC from HPN.     

Benign versus malignant hepatic nodules: MR imaging findings with pathologic correlation.

According to the currently used nomenclature, there are only two types of hepatocellular nodular lesions: regenerative lesions and dysplastic or neoplastic lesions. Regenerative nodules include monoacinar regenerative nodules, multiacinar regenerative nodules, cirrhotic nodules, segmental or lobar hyperplasia, and focal nodular hyperplasia. Dysplastic or neoplastic nodules include hepatocellular adenoma, dysplastic foci, dysplastic nodules, and hepatocellular carcinoma (HCC). Many of these types of hepatic nodules play a role in the de novo and stepwise carcinogenesis of HCC, which comprises the following steps: regenerative nodule, low-grade dysplastic nodule, high-grade dysplastic nodule, small HCC, and large HCC. State-of-the-art magnetic resonance (MR) imaging facilitates detection and characterization in most cases of hepatic nodules. State-of-the-art MR imaging includes single-shot fast spin-echo imaging, in-phase and opposed-phase T1-weighted gradient-echo imaging, T2-weighted fast spin-echo imaging with fat saturation, and two-dimensional or three-dimensional dynamic multiphase contrast material-enhanced imaging.     

Malignant hepatic tumors: Changes on MRI after hepatic arterial chemoembolization – preliminary findings

This study describes the MR appearances of malignant hypervascular liver lesions pre- and post-hepatic-arterial chemoembolization, with correlation to serial imaging and clinical responses. Eight patients with malignant hypervascular liver lesions underwent pretreatment and posttreatment MR examination on a 1.5-T MR imager. MR sequences included T1-weighted spoiled gradient echo (SGE), T2-weighted fat-suppressed spin echo or turbo spin echo, and dynamic gadolinium-enhanced SGE images. All patients underwent pretreatment, initial posttreatment, and subsequent posttreatment MR studies. The histology of primary tumors included various types of hepatocellular carcinoma (HCC) (four patients: fibrolamellar HCC [one patient], HCC [two patients], mixed HCC/cholangiocarcinoma [one patient]) and liver metastases (four patients: untyped islet cell tumor [two patients], gastrinoma [one patient], carcinoid [one patient]). Response to chemoembolization was determined by three assessments: MR response, serial imaging response, and clinical response. The appearance of MR response to chemoembolization was determined based on the correlation with clinical and serial imaging response. The MR response of lesions that showed good clinical response included: increase in signal intensity on T1-weighted images (three patients), decrease in signal intensity on T2-weighted images (three patients), and negligible or minimal enhancement on immediate postgadolinium images (four patients) after chemoembolization. The most marked change in lesion appearance was observed in lesions < 1 cm, which had intense homogeneous enhancement on pretreatment MR studies and negligible enhancement on initial posttreatment MR examinations. MR response of lesions that showed moderate clinical response demonstrated a variety of lesion appearances from substantial change to minimal change. MR response of lesions that showed poor clinical response demonstrated no change in lesion appearances compared with the pretreatment MR study. Our results demonstrated change in appearance of liver lesions between pre- and post-hepatic-arterial chemoembolization MR studies. MR response correlated with response determined by serial imaging studies and clinical findings.     

Muscular sarcoidosis

There are four types of muscular sarcoidosis: nodular, chronic myopathy, acute myositis, and asymptomatic. The nodular type is important because it may be confused with a soft tissue tumor. Magnetic resonance (MR) imaging provides specific findings. A star-shaped central structure of decreased signal intensity, a "dark star" sign, is seen on the axial images. A long nodule with an inner stripe of decreased signal intensity and outer stripes of increased signal intensity, a "three stripes" sign, is seen on the coronal and sagittal images. In the chronic myopathy type, the role of MR imaging is limited. Gallium scintigraphy, which reflects activity of inflammation, may show increased uptake. In the acute myositis type, MR imaging shows increased signal intensity, and gallium scintigraphy shows increased uptake; however, these findings are nonspecific.     

MR characterisation of dysplastic nodules and hepatocarcinoma in the cirrhotic liver with hepatospecific superparamagnetic contrast agents: pathological correlation in explanted livers

Purpose

The authors sought to evaluate the potential of magnetic resonance (MR) imaging with superparamagnetic iron oxide (SPIO) contrast material for identifying, characterising and differentiating dysplastic nodules (DN) and hepatocellular carcinoma (HCC) in the cirrhotic liver by correlating the results with pathological findings on the explanted liver.

Material and methods

MR imaging was used to study the liver of 400 cirrhotic patients awaiting liver transplantation, 31 of whom were selected to receive a liver. Of these 31 patients, we included in the study 22 patients (mean age 53 years; range 46–57 years) who underwent liver transplantation within 12–24 h after MR examination. Patients were studied with a 1.5-T device, and scans were acquired before and after the administration of paramagnetic contrast material. For every lesion, we recorded signal intensity on unenhanced baseline T1- and T2-weighted images and enhancement pattern after SPIO administration. Histological examination of the entire liver provided the definitive diagnosis of the lesions.

Results

Histological examination identified 59 lesions: 14 HCC, 4 HCC-DN, 39 DN, and 2 cystoadenomas. Among the 14 HCC, three were well differentiated, eight were moderately differentiated and three were poorly differentiated. Of the 39 DN, 28 were low-grade and 11 high-grade lesions. Unenhanced baseline MR imaging correctly identified and characterised 20 lesions, equal to 33.90% of all lesions: 6 HCC, 12 DN and 2 DN with a subfocus of HCC. SPIO-enhanced MR imaging showed greater sensitivity detecting and characterising 45 lesions, equal to 76.27% of all lesions identified at histology: 14 HCC, 27 DN and 4 DN with subfocus of HCC. SPIO administration improved the sensitivity of MR imaging in lesion detection and characterisation by 42.37%. False negative results with SPIO-enhanced MR imaging occurred in 12 DN (31%), which histological examination revealed to be low-grade DN with a diameter <1 cm.

Conclusions

SPIO-enhanced MR imaging proved to be of value in detecting and characterising lesions in the cirrhotic liver, allowing differentiation of DN from HCC and providing an early diagnosis of neoplastic degeneration of DN.     

MR imaging of the brain in Wilson disease of childhood: findings before and after treatment with clinical correlation

BACKGROUND AND PURPOSE: Although brain MR imaging findings in adult Wilson disease have been described in considerable detail, a paucity of information currently exists regarding brain MR imaging findings in pediatric Wilson disease. The purpose of this study was to analyze the brain MR imaging findings in Wilson disease of childhood at the initial stage and during follow-up after treatment and to correlate these observations with clinical response. METHODS: We evaluated 50 patients with pediatric Wilson disease. Fifty initial and 20 follow-up MR images from 15 patients following penicillamine treatment were analyzed retrospectively, and the data were correlated with clinical findings. RESULTS: Patients were categorized into 3 groups on the basis of initial MR imaging findings. Group I (n = 23) showed normal MR imaging findings. Group II (n = 15) was characterized by T1-weighted images with increased signal intensity in the globus pallidus (n = 15, 100%) followed by the putamen, midbrain, and caudate nucleus. Group III (n = 12) demonstrated T2-weighted images with increased signal intensity in the putamen (n = 10, 83%), followed by the caudate nucleus, globus pallidus, thalamus, midbrain, and pons. There was a significant difference in mean age, the presence of neurologic symptoms, and Child-Pugh classification among the 3 groups (P < .001). Following copper chelating therapy, the changes on follow-up MR imaging were strongly correlated with clinical response to treatment (P < .001). CONCLUSION: Brain MR imaging in children with Wilson disease can be categorized into distinct groups and demonstrated a significant correlation with clinical findings. Interval changes on follow-up MR imaging were also closely correlated with clinical findings and helpful in assessing the clinical response.     

不同剂量二乙基亚硝胺对诱发大鼠肝硬化多步癌变模型的影响

目的 探讨不同剂量的二乙基亚硝胺(DENA)对诱发SD大鼠肝硬化多步癌变模型的影响.方法 采取简单随机抽样方法,将50只SD大鼠分为对照组5只及实验组45只,再将实验组大鼠采用同样的随机方法分为高、中、低剂量组,每组各15只.用DENA溶液分别按每周70、50和35 mg/kg的剂量对实验组大鼠灌胃10周,对照组大鼠灌注生理盐水.从第11周起,采用上述随机方法对照组每3周取1只,实验组每周取1只行MR检查,并对可疑结节取材,进行病理观察.计算各剂量组死亡率.采用Pearson Chi-square检验比较不同剂量组间癌前病变不典型增生结节(DN)所占比例的差异.结果 该模型的病变发展经历了从肝硬化再生结节(RN)至DN,最后到肝细胞癌(HCC)的过程.2只中剂量组、4只高剂量组大鼠因HCC破裂出血于第25周死亡.实验组中,低、中、高剂量组的DN所占比例分别为20.7％ (6/29)、30.6％ (19/62)、14.3％ (9/63),总体差异无统计学意义(x2 =4.901,P＞0.05),但中、高剂量组间差异有统计学意义(x2=4.811,P＜0.05).结合MR图像,中等剂量(50 mg/kg)是较合适的诱发剂量.结论 中等剂量的DENA溶液灌胃法较适用于诱发可用于影像观察HCC癌前病变的大鼠肝硬化多步癌变模型.     

Budd-Chiari综合征的CT、MRI诊断价值

目的分析布-加氏综合征的MR、ICT的表现,进一步提高该病的诊断率。方法对经血管造影证实的15例Budd-Chiari综合征的MR、ICT表现进行回顾性分析。结果15例MRI和CT诊断均正确,2例伴多发再生结节定性诊断正确。Budd-Chiari综合征MR、CT有下列征象:(1)下腔静脉和/或肝静脉狭窄或闭塞(15例);(2)肝实质淤血肿胀伴异常密度或信号灶(12例),延迟扫描无明显强化(7例),部分可见肝实质强化逐渐均匀(5例);(3)迂曲增粗及逗点状侧枝循环(10例);(4)无肝炎背景的肝硬化、腹水,伴或不伴脾轻度肿大(4例),伴侧枝循环形成(15例);(5)多发再生结节(2例)。结论MRI、CT对Budd-Chiari综合征的诊断具有重要价值。     

Method for simultaneous voxel-based morphometry of the brain and cervical spinal cord area measurements using 3D-MDEFT

Purpose:

To develop a quantitative multiparametric PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) magnetic resonance imaging (MRI) approach and its application in a diethylnitrosamine (DEN) chemically induced rodent model of hepatocarcinogenesis for lesion characterization.

Materials and Methods:

In nine rats with 33 cirrhosis‐associated hepatic nodules including regenerative nodule (RN), dysplastic nodule (DN), hepatocellular carcinoma (HCC), and cyst, multiparametric PROPELLER MRI (diffusion‐weighted, T2/M0 (proton density) mapping and T1‐weighted) were performed. Apparent diffusion coefficient (ADC) maps, T2 and M0 maps of each tumor were generated. We compared ADC, T2, and M0 measurements for each type of hepatic nodule, confirmed at histopathology.

Results:

PROPELLER images and resultant parametric maps were inherently coregistered without image distortion or motion artifacts. All types of hepatic nodules demonstrated complex imaging characteristics within conventional T1‐ and T2‐weighted images. Quantitatively, cysts were distinguished from RN, DN, and HCC with significantly higher ADC and T2; however, there was no significant difference of ADC and T2 between HCC, DN, and RN. Mean tumor M0 values of HCC were significantly higher than those of DN, RN, and cysts.

Conclusion:

This study exploited quantitative PROPELLER MRI and multidimensional analysis approaches in an attempt to differentiate hepatic nodules in the DEN rodent model of hepatocarcinogenesis. This method offers great potential for parallel parameterization during noninvasive interrogation of hepatic tissue properties. J. Magn. Reson. Imaging 2010;31:1242–1251. © 2010 Wiley‐Liss, Inc.     

Cirrhotic nodules: association between MR imaging signal intensity and intranodular blood supply

PURPOSE: To retrospectively determine whether there is a relationship between the intranodular blood supply evaluated at computed tomography (CT) during arterial portography (CTAP) and CT during hepatic arteriography (CTHA) and the magnetic resonance (MR) imaging signal intensity of nodules associated with cirrhosis. MATERIALS AND METHODS: Neither institutional review board approval nor informed consent was required for retrospective reviews of medical records and images. One hundred fourteen hepatocellular nodules 10 mm or greater in largest diameter in 58 patients (39 men, 19 women; mean age, 61 years) with cirrhosis were evaluated at CTAP, CTHA, and MR imaging. The CTAP and CTHA nodule findings were divided into three main types: Type A nodules were isoattenuating at CTAP and hypoattenuating at CTHA; type B nodules, slightly hypoattenuating at CTAP and hypoattenuating at CTHA; and type C nodules, strongly hypoattenuating at CTAP and hyperattenuating at CTHA. The relationships between the CTAP and CTHA findings and the MR imaging signal intensity among these nodules were analyzed by using the chi(2) test. RESULTS: On T1-weighted MR images, 27 (63%) of 43 type A nodules were hyperintense, nine (39%) of 23 type B nodules were isointense, and 19 (48%) of 40 type C nodules were hypointense; differences were not significant. On T2-weighted MR images, 31 (72%) of 43 type A nodules were hypointense (P < .05), 12 (52%) of 23 type B nodules were isointense, and 34 (85%) of 40 type C nodules were hyperintense (P < .05). CONCLUSION: There was a significant association between intranodular blood supply and nodule signal intensity on T2-weighted MR images. However, study findings did not show whether the blood itself (ie, blood volume or blood flow amount) directly influenced the signal intensity.     

大鼠肝硬化肝癌SPIO增强MRI表现与Kupffer细胞的关系

目的：建立二乙基亚硝胺（DENA）诱导的大鼠肝硬化肝细胞癌（HCC）模型,探讨超顺磁性氧化铁（SPIO）增强MRI上肝硬化肝癌信号改变与肝Kupffer细胞（KCs）之间的关系。方法：22只大鼠肝硬化肝癌模型,其中6只为单纯性肝硬化,16只为肝硬化肝癌,对照组为10只清洁级Wistar雄性大白鼠,均行SPIO增强前后T1WI和T2WI扫描,并行病理检查（HE染色及普鲁士蓝染色）,分析肝脏Kupffer细胞数量与SPIO增强后信号之间的关系。结果：普鲁士兰染色切片上肝硬化组织内蓝染Kupffer细胞数量略减少,蓝色颗粒不均匀;高分化肝癌中Kupffer细胞减少,低分化肝癌Kupffer细胞显著减少甚至消失。肝癌与正常肝实质、硬化肝组织相比,Kupffer细胞数量减少,差异有显著性意义（P〈0．001）;正常肝实质与肝硬化组织内Kupffer细胞数量的差异无显著性意义（P＝0．088）。SPIO增强T2WI上,正常肝实质、肝硬化组织信号强度（SI）较增强前明显下降,信号强度下降百分比（PSIL）分别为42％和38％,两组间差异无统计学意义（P＝0．409）;肝癌信号强度较增强前无明显下降,PSIL为12％,明显低于正常肝实质和肝硬化组织（P〈0．001）;SPIO增强后肝癌对比噪声比（CNR）较增强前显著提高（P＝0．002）。SPIO增强T1WI上。正常肝实质及硬化肝组织PSIL分别为15％和6％,而肝癌的信号强度较增强前升高9％,部分小病灶呈不均匀轻度强化,肝癌CNR较增强前明显降低（P〈0．001）。SPIO增强T2WI上,肝组织PSIL与Kupffer细胞数量呈曲线趋势,随着组织内Kupffer细胞数量的增多病灶信号强度下降程度越明显,曲线估计3次模型决定系数R^2为0．920,有显著性意义（P〈0．001）。结论：SPIO增强T2WI上肝脏信号强度改变与Kupffer细胞数量及其吞噬功能有相关性,随着Kupffer细胞增多PSIL呈升高趋势。SPIO增强MRI不?     

The value of gadobenate dimeglumine-enhanced delayed phase MR imaging for characterization of hepatocellular nodules in the cirrhotic liver

OBJECTIVES: To evaluate the value of 1-hour delayed phase imaging (DPI) of gadobenate dimeglumine (Gd-BOPTA)-enhanced MR imaging for the characterization of hepatocellular carcinoma (HCC) and dysplastic nodule (DN) in patients with cirrhosis. MATERIALS AND METHODS: A total of 37 patients with 42 HCCs and 13 DNs were included in this study and all lesions were histopathologically confirmed except for 15 HCCs. T1-weighted 3-dimensional gradient-echo images were acquired before, immediately after (30, 60, 180 s), and 1 hour after bolus injection of gadobenate dimeglumine at a dose of 0.1 mmol/kg. The lesions were classified as isointense, hypointense, or hyperintense compared with the surrounding liver parenchyma on DPI for qualitative assessment. We performed quantitative analyses of the contrast-to-noise ratio (CNR) and of the relative contrast enhancement of the lesion on the DPI. RESULTS: In the qualitative analysis, among 42 HCCs, 30 (71.4%) were hypointense on DPI, and 10 (23.8%) and 2 (4.8%) were isointense and hyperintense, respectively; only 1 of 13 DNs (7.7%) was hypointense and 10 (76.9%) and 2 (15.4%) were isointense and hyperintense, respectively. In contrast, 25 HCCs (71.4%) of 35 hypervascular HCCs were hypointense on DPI, and no hypervascular DN (0/7) was hypointense with statistical significance (P = 0.0007). When we considered the hypointensity of the hepatic lesions on delayed phase as a sign of HCC in cirrhotic liver, our results gave a sensitivity of 71.4% and a specificity of 91.7%. In the quantitative analysis, the mean CNR of the HCCs and the DNs on the 1-hour DPI was -6.32 +/- 6.27 and -0.07 +/- 3.28, respectively; the difference between the HCCs and the DNs was significant (P < 0.05). CONCLUSIONS: Delayed gadobenate dimeglumine-enhanced MR imaging allows improved characterization of HCC in cirrhotic liver. The relative hypointensity to adjacent normal liver parenchyma is a reliable predictor that this lesion favors HCC rather than DN in cirrhotic liver.     

MR imaging of hepatocellular carcinoma: relationship between lesion size and imaging findings, including signal intensity and dynamic enhancement patterns

PURPOSE: To assess the relationship between lesion size and MR imaging findings of pathologically-proven hepatocellular carcinoma (HCC). MATERIALS AND METHODS: In a retrospective, single-center study, 37 consecutive patients were identified between 1999 and 2005 that underwent preoperative MRI and surgical resection of HCC. A total of 47 lesions (mean size = 6.85 cm, range = 1-25 cm) were assessed for signal intensity (SI), enhancement patterns, and secondary morphologic features. Interobserver rating, percentage enhancement, and contrast-to-noise-ratio (CNR) were determined. Lesions were assessed for combinations of typical MRI features. Regression analysis was used to assess relations between MRI findings and tumor size. RESULTS: On fat-suppressed T2-weighted (T2w) fast-spin-echo, smaller lesions had lower SI compared to larger lesions (P < 0.05). In the arterial phase, smaller lesions showed significantly higher percentage enhancement compared to larger lesions (P < 0.05). In the delayed phase, smaller lesions showed less pronounced washout (P < 0.05). Heterogeneity of the lesions, including fatty infiltration, internal nodules, or mosaic pattern, was observed significantly more frequently in larger lesions (P < 0.001). The classic combination of high T2w signal, strong arterial enhancement, and delayed phase washout was present in 23 of 44 lesions (52%). CONCLUSION: Smaller HCC often showed lower SI on T2w, more intense arterial enhancement, and less pronounced delayed washout compared to larger HCC.     

Hepatocellular carcinoma: association with increased iron deposition in the cirrhotic liver at MR imaging.

PURPOSE: To determine whether the frequency of hepatocellular carcinoma (HCC) in patients with cirrhosis is affected by hepatic iron deposition as detected with magnetic resonance (MR) imaging. MATERIALS AND METHODS: In a retrospective search of MR imaging and histopathology records, 196 patients with histopathologically proved cirrhosis and with (n = 80) or without (n = 116) HCC who underwent T2-weighted conventional or fast spin-echo and gradient-echo (GRE) (echo time > or = 6.0 msec) imaging were identified. MR images were qualitatively and quantitatively evaluated for diffuse hepatic iron deposition and siderotic regenerative nodules to assess their correlation with the presence of HCC. RESULTS: Hepatic parenchymal iron deposition was seen in 79 (40%) patients, and iron deposition in regenerative nodules was seen in 71 (36%) at MR imaging. The mean signal intensity ratio of GRE images in patients with hepatic iron deposition was significantly lower than that in patients without it (P < .001). The frequency of HCC in patients with iron deposition in regenerative nodules (52% [37 of 71 patients]) was significantly higher (P = .015) than that in patients without iron in regenerative nodules (34% [43 of 125 patients]). CONCLUSION: The occurrence of HCC may be associated causally with iron deposition in regenerative nodules in patients with cirrhosis. MR imaging can enable detection of iron deposition in regenerative nodules as a possible risk factor for the development of HCC.     

超顺磁性氧化铁在大鼠诱癌模型磁共振诊断与鉴别诊断中的作用

目的研究超顺磁性氧化铁(SPIO)在大鼠诱癌模型的磁共振成像中对增生性结节与肝癌的鉴别作用，以及SPIO增强前后对各型肝癌的检出率。材料与方法42只诱发型肝癌模型鼠在肝硬化多发增生性结节基础上，共计生成379个肝癌，行平扫及SPIO增强扫描，分析增生性结节与肝癌的不同强化方式，并与病理对照统计平扫与增强扫描各型肝癌的检出率。结果增生性结节在SPIO增强扫描T2WI上信号明显降低，而肝癌的信号无明显改变；肝癌SPIO增强扫描T2WI检出率与病理接近，而平扫T2WI检出率与病理相差显著，其中平扫微癌与小癌的漏检率分别达32．9％与12．9％。结论SPIO是一种有效的检测肝癌的磁共振对比剂，不仅能提高小肝癌的检出率而且对增生性结节与肝癌的鉴别提供帮助。     

MRI evaluation of acute renal trauma

We describe the MR findings in a patient with acute renal injury after blunt abdominal trauma associated with perinephric hematoma and urinoma. Both CT and MR findings are described. Active urine extravasation into a perinephric urinoma is demonstrated by serial post-contrast imaging with CT and MRI showing progressively increased attenuation/signal intensity fluid in communication with the collecting system, commencing 2 minutes after contrast administration.     

Invited. Hepatitis,cirrhosis, and hepatoma

Virus hepatitis and liver cirrhosis are found at high incidence in Asia, and they require not only biochemical examination of blood but also subsequent imaging, because they are often complicated by hepatocellular carcinoma (HCC). It is, therefore, very important to know the specific appearances of hepatitis, liver cirrhosis, and HCC when we diagnose these diffuse liver diseases. Liver necrosis due to severe hepatitis is seen as high intensity on T2-weighted spin echo images. Regeneration is seen as low intensity on T2-weighted images. Morphologic and pathologic changes of cirrhotic liver are well demonstrated by MR imaging techniques. Fibrotic septum with inflammatory cell infiltration or rich pseudo bile duct show high intensity on T2-weighted images, and regenerating nodules shows low intensity. Gradient echo images show regenerating nodules with iron deposition as low-intensity nodules due to susceptibility artifact. MRI also has the potential to evaluate function of diffuse liver disease, cirrhosis, and hepatitis. MRI can visualize and diagnose HCC objectively. Dynamic MRI is very useful for diagnosing HCC. It is also applied for evaluation of effect after transcatheter arterial chemoembolization, because it shows enhancement only in the viable region at an arterial phase. MRI is less invasive and is thus an extremely important form of liver imaging.